1. Field
The present disclosure relates generally to a safety valve for gaseous and/or liquid fuel or other chemical lines, and more particularly, to a self-contained safety valve for gaseous or liquid fuel or other hazardous chemical lines which automatically closes the flow of gaseous or liquid fuel or other hazardous chemical when the surrounding temperature or the temperature of the gaseous or liquid fuel or other chemical substances passing through the valve rise above a predetermined threshold temperature.
2. Prior Art
There are currently devices known in the art for shutting the flow of gas such as natural gas or liquid fuel in homes or in commercial buildings in case of fire that operate based on an external and powered sensor to monitor the temperature and then command certain actuation device such as an electrically powered solenoid to actuate a valve or cause it to actuate a valve to close the flow of said gaseous or liquid fuel.
The currently available methods and devices are complex, expensive, generally require external power (either battery or line power) and the externally actuated valves require sealing of moving parts, which are prone to wear, and when made out of plastics are subject of aging and hardening and cracking, and thereby leakage, particularly for the case of gaseous fuel such as natural gas or propane and certain chemicals. In addition, for battery operated systems, the users often forget to test and change the batteries and for line powered devices the power may be out or go out or disconnected in case of fire or the like.
Valves using shape memory alloy actuation devices for preventing the flow of fluid when the temperature of the fluid is above a predetermined threshold is also disclosed in the U.S. Pat. No. 8,695,889. The valve is designed to allow the fluid to pass when the temperature of the fluid is below the predetermined threshold, and used a shape memory or bi-metal actuator for substantially closing the flow passage when the temperature of the fluid is above the predetermined threshold. Such valves, however, are not designed for closing the flow passage when heated either by the passing flow or from outside the valve.